I Know Things Now

Edie hires a private investigator, Oliver Weston, to determine if Karl was cheating on her with another woman. When Weston arrives on Wisteria Lane, he hides in the bushes of a neighboring home and records Karl and Susan talking in the garage about their one night stand. Weston is soon discovered by Mike Delfino who asks him why he is snooping around. When Weston attempts to explain why he is there, Mike punches him in the face after he mocks Susan. Later, Mike invites Susan over and introduces her to Weston and his mission. Weston plays a tape revealing her affair with Karl and Susan is shocked. She tries to buy Weston off, but he names an exorbitant price and gives her an ultimatum to come up with the money by the following Monday or he will hand over the information to Edie. Susan cannot afford the money and therefore writes Edie a letter of apology detailing her fling with Karl. After mailing the letter, Mike visits Susan to tell her that he paid Weston's bribe because he doesn't want anyone to get hurt. Susan is relieved and thanks Mike for preventing a war between herself and Edie. Susan then must come up with a way to get her letter back. Following a sudden inspiration she lures the mailman into her kitchen with iced tea. After she has plied him with enough tea, Susan suggests he use the restroom upstairs by her bedroom as the one nearby is broken. Susan then steals the letter from his bag and puts it with her mail. After he has been upstairs for a while, Susan worries about the mailman and is surprised to find him on her bed in his undergarments. Susan warns him to get dressed since her daughter is home. Downstairs, Julie checks the mail and puts Edie's letter back in the sack. Susan then hurries the mailman out and declines a rain check. Edie soon discovers the letter and while Susan is at Mike's, Edie drenches Susan's house in kerosene and sets it on fire.

Gabrielle, still distraught over losing baby Lily, invites the wives over for food and consoling. Xiao-Mei also is upset because she is being deported after several warning notices. Gabrielle and Carlos then visit with Homeland Security where the agent explains to them that if Xiao-Mei were pregnant with or married to an American citizen, she would be allowed to remain the country. Gabrielle then asks Xiao-Mei if she will have their baby since they consider her family. Xiao-Mei declines the offer since she values virginity and if she were to marry, her husband will not want her. Gabrielle insists Americans do not believe this and convinces Xiao-Mei to reconsider. On the morning of the insemination, Carlos finds a confused Xiao-Mei naked in bed ready for her first intimate moment. Gabrielle soon discovers Carlos and Xiao-Mei and puts an end to Carlos's ogling.

Tom comes to final blows with Ed when Ed hires a forensic accountant to find reason to fire him. Tom saves Ed the time by punching him in the face and making sure that he gets himself fired. Lynette confronts Ed and refuses to apologize for what her husband did and says none of it would have happened if Ed handled his marriage better. Ed retorts that she should not pass judgment on his marriage since her marriage is flawed as well. Ed tells Lynette about Tom's expense account; including an unauthorized trip to Atlantic City with a show for two and flowers. Lynette later meets Tom in the lobby after he has cleaned out his office. Lynette then asks if he wants to tell her anything. Tom has nothing to say and leaves in the elevator.

Betty plans to kill Caleb by taking him to a picnic and feeding him ice cream she prepared with drugs. At the lake, Caleb asks where Matthew is and Betty says it is a special day just for the two of them. Caleb then tells his mother that Matthew told him to kiss Danielle and that she would be waiting for him. Betty then takes the ice cream from Caleb and demands that he tell her everything Matthew told him to do. Later, Betty locks Matthew in the basement for his treachery.

Bree invites Peter for dinner and also asks that Andrew bring Justin as well. When Bree tells Peter of the dinner plans, he reluctantly gives in, feeling uncomfortable because of his sex addiction. Andrew overhears their conversation on another phone and asks Danielle to help him with a scheme. During dinner, Danielle comes to dinner in a revealing outfit in an attempt to mess with Peter. When she succeeds in flustering him by running her hand up his thigh, Peter unexpectedly leaves saying his sponsor needs him at a meeting. The following day, Andrew tries to get Danielle to sleep with Peter. Danielle tells Andrew to get out of her room and calls him a psycho. Andrew invites Peter over and asks about his sex addiction and previous sexual encounters. Peter says that he "slept with a lot of people back then." Andrew then realizes that Peter is bisexual. Capitalizing on this, Andrew seduces him. Bree soon arrives home after being called by Andrew, and is shocked to find Andrew in her bed with Peter coming out of her bathroom half-naked and looking for his pants. The next day, Bree takes Andrew to take a tour of his desired college. However, halfway there, Bree leaves Andrew at a gas station, tells him she can't be around him anymore, and gives him money and clothes with the understanding that he is now on his own. Initially Andrew pleads for her not to leave him there but then declares that he has won since he knew ever since he came out and saw a certain look in her eye that she would eventually stop loving him. With a tortured resolve born out of her intense sadness, Bree just looks back at him, and despondently says, "Well, good for you," then returns to her car. As Bree looks back at Andrew from the rear view mirror, she begins to weep.

Although credited, Paul Young (Mark Moses), Zach Young (Cody Kasch), Preston Scavo (Brent Kinsman), Porter Scavo (Shane Kinsman), and Parker Scavo (Zane Huett) do not appear in this episode.

"I Know Things Now" received mixed to positive reviews from critics and viewers.

Parents Television Council, a Christian conservative "responsible entertainment" advocacy watchdog, writer Joshua Shirlen named "I Know Things Now" the Worst TV Show of the Week following its original airing for, in his words, featuring "adultery, nudity, and teen sex." In the article, Shirlen claims the 2006 episode "trivializes adultery, virginity, sexual addictions, and teen sex" when further justifying the title of Worst of the Week.

• The episode title is that of the song "I Know Things Now" sung by Little Red Riding Hood in the Stephen Sondheim musical, Into the Woods.

• French: L'envie de savoir (The urge to know)
• German: Rache (Revenge)
• Italian: Adesso Lo So (Now I Know)
• Hungarian: Bosszú (Revenge)
• Polish: Rewanż (Revenge)